Various types of resins will find a wide variety of uses, among which will be printing inks and coatings for the graphic arts and packaging industries. Prior resins have included acrylated urethanes. These resins are formed by the reaction of a hydroxyacrylate monomer with an isocyanate monomer or prepolymer and may be based on a wide range of aromatic and aliphatic isocyanates. Multifunctional acrylate monomers such as, for example, trimethylolpropane triacrylate, may be combined with the acrylated urethanes in order to reduce the viscosity of the resin and increase the cross-linked density of the cured material. The acrylated urethanes may be cured by a free radical polymerization of the acrylate group, this being accomplished by ultraviolet irradiation in the presence of a photoinitiator or by electron beam irradiation. The radiation-cured acrylated urethanes may be used in printing inks, floor coatings, automotive coatings, printed circuit board coatings, etc. However, the acrylates possess an inherent disadvantage in that the monomers are known to be toxic whereby a hazard to the general health of either the user or the public at large is created.
Vinyl ethers constitute extremely reactive monomers which are known to polymerize by a cationic mechanism. These compounds may be useful in applications which require a high speed curing of a resin formulation. The vinyl ethers react much faster than the epoxy resins and therefore may be used for printing inks, coatings, elastomers, foams, or in other types of materials dependent upon the ability of the resin to cure at a rate which is contiguous with other processing steps. One disadvantage which is attendant to the vinyl ethers is that the commercial availability of these ethers is relatively limited. In general, the vinyl ethers which are available constitute low molecular weight monofunctional or difunctional monomers. However, in most commercial applications, the use of higher molecular weight polymer resins constitutes the preferred species. This is due to the fact that the higher mole weight materials are non-volatile and will possess more desirable rheological properties, and they permit greater control of the properties of the finished product.
As will hereinafter be shown in greater detail, it has now been discovered that it is possible to obtain vinyl ether terminated urethane resins which will constitute novel compositions of matter and which will possess characteristics which make them desirable for use in various commercial applications.
The aforesaid vinyl ether terminated urethane resins which are formed by the process hereinafter described in greater detail may be subjected to a curing treatment to provide tack-free coatings.